Add a note for removing old archives in the installer README
Add a note for removing old archives in the installer README

jwarwick/phoenix,nshafer/phoenix,jwarwick/phoenix,Gazler/phoenix,phoenixframework/phoenix,evax/phoenix,mitchellhenke/phoenix,Kosmas/phoenix,eksperimental/phoenix,optikfluffel/phoenix,phoenixframework/phoenix,Joe-noh/phoenix,nshafer/phoenix,optikfluffel/phoenix,evax/phoenix,pap/phoenix,michalmuskala/phoenix,rafbgarcia/phoenix,phoenixframework/phoenix,0x00evil/phoenix,mitchellhenke/phoenix,Joe-noh/phoenix,michalmuskala/phoenix,Gazler/phoenix,keathley/phoenix,0x00evil/phoenix,dmarkow/phoenix,eksperimental/phoenix,dmarkow/phoenix,optikfluffel/phoenix,pap/phoenix,rafbgarcia/phoenix,keathley/phoenix,mobileoverlord/phoenix,mobileoverlord/phoenix,mschae/phoenix,nshafer/phoenix,0x00evil/phoenix,Kosmas/phoenix,mschae/phoenix,rafbgarcia/phoenix